DENVER -- The Rockies have spent their two decades in the Majors trying to develop pitchers who can survive at Mile High atmosphere. MLB.com's current list of the organization's top 20 prospects suggests the team is making strides in that area.

Colorado's top pick in the 2013 MLB First-Year Player Draft, Oklahoma right-hander Jonathan Gray, selected third overall, immediately was placed at the top of the Rockies' list, and two pitchers who weren't in the top five at the start of the year are now. Right-hander Eddie Butler, a supplemental first-round choice last year out of Radford University, has leaped from No. 10 to No. 3, and left-hander Tyler Anderson, the top pick in 2011 out of Oregon, is up one spot to No. 5.

Interestingly, the pitcher on the list who could make an impact as early as this season actually fell five spots. Right-hander Chad Bettis, a second-round pick out of Texas Tech in 2010, dropped from No. 4 to No. 9. Bettis battled an oblique injury early this season, but after his return, club officials said he was on target for the big league club, which is trying to solidify the back of its rotation.

Graduated
Third baseman Nolan Arenado entered the season No. 2 on the Rockies' prospect list, but he was clearly No. 1 in terms of those watching the big league club for immediate help. Arenado was in the Majors before the end of the season's first month.

Arenado, 22, was touted for his hitting, but his first months in the bigs have been a study in adjusting to higher level pitching. However, he has performed well enough defensively that many see him as a candidate for a Rawlings Gold Glove Award.

Dropped off
A supplemental first-round pick in 2010, right-handed pitcher Peter Tago has had trouble getting traction to his career. He went form short-season Class A Tri-City to Rookie-level Grand Junction, and from No. 16 to nowhere on the list.

Righty Joe Gardner, obtained from the Indians in the 2011 trade that sent away pitcher Ubaldo Jimenez, entered ranked 17th, but pitched himself off the Major League roster and lost his spot on the list.

New faces
Gray, who was in the conversation to be the No. 1 overall pick, brings the type of power the Rockies like. He exceeded 100 mph on several occasions in college. The Rockies sent him to Rookie-level Grand Junction to work on adding a changeup to his fastball and slider.

Catcher Tom Murphy wasn't on the list at the start of the year, but his performance at Class A Asheville allowed him to enter at No. 6. Murphy, a third-round pick in 2012 out of the University of Buffalo, has impressed the Rockies with his physical strength, not only in terms of offensive power but ability to handle the long season. Having former Rockies catcher coach Marv Foley at Ashevlle as development coordinator has shortened his defensive learning curve.

Third baseman Ryan McMahon, a football and baseball star at Mater Dei High School in Santa Ana, Calif., got off to a .326 start at Grand Junction and made the list at No. 19.

rockies' top prospects

Rising/falling stock
The biggest rise was by outfielder Corey Dickerson, who was so dominant at Triple-A Colorado Springs that he earned a brief callup to the Majors. Dickerson began the year ranked 19th, and now checks in at No. 8.

Shortstop and third baseman Rosell Herrera, who signed out of the Dominican Republic for $550,000, hit a combined .241 at Tri-City and Asheville. Through Wednesday, he was hitting .360 with 15 home runs and 65 RBIs at Asheville this year, a performance that led to a rise from 12th to fourth.

Herrera's rise coincided with a slight fall by shortstop Trevor Story, a supplemental first-round pick out of Irving (Texas) High School, who struggled at Class A Modesto this year and went from fourth to seventh on the list.

Last year's top Draft pick, outfielder David Dahl, topped the list last year and is No. 2 this time. After a standout 2012 at Tulsa, Dahl spent much of the early season at extended spring training for disciplinary reasons. He had built decent numbers at Asheville before he suffered a hamstring injury that has him out of action.

Top 100 representation
Gray joins the MLB.com Top 100 Prospects list at No. 37, as he begins his adjustment to pro ball. The Rockies are closely monitoring the number of combined innings in college and pro ball, and hope not to extend him to the point of injury.

Dahl's early-season troubles led to a slight drop on the Top 100, from 59th to 60th.

Butler, not on the Top 100 at the start of the year, comes in at No. 97.

The prospects led to a No. 20 overall placing for the Rockies' farm system in the MLB.com rankings.